{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "w 是以写的方式打开文件 write\n",
    "a 是以追加的方式打开文件 append\n",
    "r 是读的方式打开文件 read"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "poem = '\\n让我们一起学习AI python\\n'\n",
    "f = open('./test/poem.txt', 'a')\n",
    "f.write(poem)\n",
    "f.close()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "让我们一起学习AI python\n",
      "\n",
      "让我们一起学习AI python\n",
      "\n"
     ]
    }
   ],
   "source": [
    "f = open('./test/poem.txt', 'r')\n",
    "data = f.read()\n",
    "print(data)\n",
    "f.close()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "让我们一起学习AI python\n",
      "\n",
      "让我们一起学习AI python\n",
      "\n"
     ]
    }
   ],
   "source": [
    "with open('./test/poem.txt', 'r') as f:\n",
    "    data = f.read()\n",
    "    print(data)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "readline方法每次读出一行内容，所以读取时占用的内存小，比较适合大文件"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "\n",
      "让我们一起学习AI python\n",
      "\n",
      "\n",
      "\n",
      "让我们一起学习AI python\n",
      "\n"
     ]
    }
   ],
   "source": [
    "f = open('./test/poem.txt', 'r')\n",
    "line = f.readline()\n",
    "while line:\n",
    "    print(line)\n",
    "    line = f.readline()\n",
    "f.close()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "readlines方法读取整个文件所有行，保存在一个列表变量中，每行对于列表的一个元素，但是读取大文件会比较占内存"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "\n",
      "让我们一起学习AI python\n",
      "\n",
      "\n",
      "\n",
      "让我们一起学习AI python\n",
      "\n"
     ]
    }
   ],
   "source": [
    "f = open('./test/poem.txt', 'r')\n",
    "lines = f.readlines()\n",
    "for line in lines:\n",
    "    print(line)\n",
    "f.close()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "poem = '\\n让我们一起学习AI python\\n'\n",
    "f = open('./test/poem.txt', 'w', encoding='utf-8')\n",
    "f.write(poem)\n",
    "f.close()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "\n",
      "让我们一起学习AI python\n",
      "\n"
     ]
    }
   ],
   "source": [
    "f = open('./test/poem.txt', 'r', encoding='utf-8')\n",
    "line = f.readline()\n",
    "while line:\n",
    "    print(line)\n",
    "    line = f.readline()\n",
    "f.close()"
   ]
  }
 ],
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